1. Field of the Invention
The present invention relates to an image reading apparatus, a method of reading an image, and an image reading system and particularly relates to an image reading apparatus, a method of reading an image, and an image reading system which are suitable for use in optically reading an image displayed on a so-called electronic paper.
2. Description of the Related Art
As the need to share electronic documents and paper documents increases, the use of electronic paper (digital paper) becomes advantageous as it possesses both the properties of an electronic display and a paper medium. Electronic paper includes an information storing section which stores information and a thin image display surface which displays the information stored in a memory (for example, see FIG. 5 of Japanese Patent Application Laid-Open (JP-A) No. 9-101864 and paragraph 5 of JP-A No. 2002-104721).
In the electronic paper, various images are displayed by a dot structure. Accordingly, in the case where a copying machine copies the image displayed on the electronic paper, when reading resolution, light quantity, and the like are set the same as for a paper medium, the dot structure and the reading resolution may interfere with each other to generate moire.
The copying machine can prevent the moire, if the dot structure of the electronic paper is recognized in advance. The dot structure of the electronic paper differs according to an image display mode. If the copying machine can distinguish a recording mode (the image display mode) of the electronic paper, the copying machine can detect the dot structure.
For example, JP-A No. 2002-104721 describes distinguishing one of an electrophoresis mode, a thermal rewritable mode, and a liquid crystal mode as the image display mode of an electronic paper.
However, when the technique described in JP-A No. 2002-104721 is adopted for a copying machine, there is a problem in that a configuration of the copying machine becomes very complicated.
Subjects of copying machines include reflective/transparent originals of a photograph, printed matter, an object printed with a laser printer or an inkjet printer, a hand-drawn document, a drawing, a picture, and the like. That is to say, copying machines do not copy an original which emits light itself.
Displays which are not provided with a light source like the thermal rewritable mode, self-light-emitting type displays such as an electroluminescent (EL) display which utilize organic EL or inorganic EL, a field emission display (FED), and a plasma display, and displays which are provided with a display section and a backlight (light source) like a liquid crystal display are included among the displays of the electronic paper. However, current copying machines have the problem that an image displayed on the electronic paper can not be copied with high quality corresponding to these various image display modes of the electronic paper.
Further, there is a high possibility of generating a flaw on a surface of the electronic paper, because the electronic paper is used repeatedly. In this case, when a copying machine reads the electronic paper with the flaw, there is a possibility of generating a defect in the read image, so that there is also the problem that the image can not be copied with high quality.
The electronic paper is treated like a paper medium. For example, sometimes letters and symbols are written on the electronic paper. In this case, there is a need for the original information recorded in the electronic paper and the handwritten information to be read while distinguishing the original information from the handwritten information. However, current copying machines and image reading apparatuses can not read both the original information recorded in the electronic paper and the handwritten information while distinguishing the original information from the handwritten information.